Often, we want to send an email whenever certain events occur, such as a new resource being created.

Before we learn how to send emails, we're going to learn how to set up our app so that certain events can trigger methods based on rules we set up.

ActiveRecord Callbacks

Callbacks are a feature in ActiveRecord that allow you to run a specified method in a model whenever a particular model is created, saved, updated and more.

Commonly Used

ActiveRecord Callbacks

• before_create
• before_save
• before_update
• after_create
• after_save
• after_update

ActiveRecord Callbacks

Rails Guide

http://edgeguides.rubyonrails.org/active_record_callbacks.html

ActionMailer

Rails has a built-in way to make mail work easily on your app.

http://guides.rubyonrails.org/action_mailer_basics.html

Generate

rails g mailer UserMailer

Create Mailer Action

Similar to a Controller Action

# mailers/user_mailer.rb

def welcome_email(user)
  @user = user
  mail(to: @user.email, subject: "Welcome!")
end

Create Mailer View

Similar to an Action View

In views/user_mailer/welcome_email.html.erb:

Hello! This is an email that we are sending you, and we can use HTML in it!
<br/><br/>
See?

Send!

Usually in the controller:

UserMailer.welcome_email(current_user).deliver

Code-Along: Tasky Emails!

Let's experiment with a few different callbacks to verify that we can trigger behavior upon certain actions.

Then, let's extend the Tasky project management app to send an email to the assignee of a task whenever it is updated.

View Solution

Sample ActionMailer Config

  config.action_mailer.raise_delivery_errors = true
  config.action_mailer.perform_deliveries = true
  config.action_mailer.default_url_options = { host: 'localhost:3000' }
  config.action_mailer.smtp_settings = {
    address: "smtp.gmail.com",
    port: 587,
    domain: "localhost:3000",
    authentication: "plain",
    enable_starttls_auto: true,
    user_name: ENV["GMAIL_USERNAME"],
    password: ENV["GMAIL_PASSWORD"]
  }

What is ENV?

ENV is the way you can access environment variables within Rails. If you are using sensitive information (such as your email passwords), you do not want to store them in code (since they get deployed to a public GitHub repository).

Instead, place environment variables inside your ~/.bash_profile or equivalent:

export GMAIL_USERNAME='your.username@gmail.com'
export GMAIL_PASSWORD='your_password'

Then reference them in your Rails app:

  user_name: ENV["GMAIL_USERNAME"],
  password: ENV["GMAIL_PASSWORD"]

Exercises

http://iexperience.github.io/exercises/12B.html